Originally Posted by
kris5597
Yes, that's exactly how it should go. However, on the 2015 GT engine, stock VCT is 0 overlap at peak power. I feel that retarding the cam more with 0 overlap to begin, will not do anything but cause issues. The intake cam retard at peak power is 14 degrees after TDC and the exhaust valve retard is also 14 degrees after TDC. Creating some overlap with an increase in airflow (intake, exhaust, etc) I feel the engine could possibly benefit from a little overlap. Considering torque and VCT both start decreasing immediately after 4500 together, gives me reason to believe the issue is a cork in airflow from both intake and exhaust side. I feel with a short runner and higher flowing intake manifold and long tube headers, valve overlap will show to be what is considered and expected as "normal" from a tuners eyes. I've never seen an engine have intake opening and exhaust closing after TDC, normally I've seen overlap with the intake cam always being advanced and the exhaust cam either being fixed at TDC or retard after TDC. New animal for me.